L1011 flight crew on ferry flight has altitude deviation as FMS fails to capture the altitude.

Attributes
ACN	334840
Time
Date	199605
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : ewm
State Reference	TX
Altitude	msl bound lower : 33000 msl bound upper : 33400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zab
Operator	common carrier : air carrier
Make Model Name	L-1011 Tri-Star All Series
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 14000 flight time type : 600
ASRS Report	334840
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

While operating an L1011 maintenance ferry from mzj to mia, experienced a failure of autoplt altitude capture when aircraft reached FL330 as assigned by ATC. Aircraft was climbing in VNAV on FMS with all appropriate autoflt 'armed' annunciations. As FL330 was approached aircraft began precapture of altitude. No capture occurred and aircraft continued to climb approximately 350 ft above FL330 before climb reversed and aircraft returned to assigned flight level. Flight continued to destination without further altitude acquisition/capture problems. Suspect this was one time anomaly resulting from combination of low gross weight (ferry trim) and high climb thrust.

Original NASA ASRS Text

Title: L1011 FLC ON FERRY FLT HAS ALTDEV AS FMS FAILS TO CAPTURE THE ALT.

Narrative: WHILE OPERATING AN L1011 MAINT FERRY FROM MZJ TO MIA, EXPERIENCED A FAILURE OF AUTOPLT ALT CAPTURE WHEN ACFT REACHED FL330 AS ASSIGNED BY ATC. ACFT WAS CLBING IN VNAV ON FMS WITH ALL APPROPRIATE AUTOFLT 'ARMED' ANNUNCIATIONS. AS FL330 WAS APCHED ACFT BEGAN PRECAPTURE OF ALT. NO CAPTURE OCCURRED AND ACFT CONTINUED TO CLB APPROX 350 FT ABOVE FL330 BEFORE CLB REVERSED AND ACFT RETURNED TO ASSIGNED FLT LEVEL. FLT CONTINUED TO DEST WITHOUT FURTHER ALT ACQUISITION/CAPTURE PROBS. SUSPECT THIS WAS ONE TIME ANOMALY RESULTING FROM COMBINATION OF LOW GROSS WT (FERRY TRIM) AND HIGH CLB THRUST.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.